Means for controlling the output of variable displacement pumps



y 5 G. J. E. sowARD 2,597,799

MEANS FOR CONTROLLING THE OUTPUT OF VARIABLE DIS PLACEMENT PUMPS Filed March 14, 1949 3 Sheets-Sheet 1 FIG! ENVENTOR ATTORNEYiQ y 20, 1952 G. J. E. HOWARD 2,597,799

MEANS FOR CONTROLLING THE OUTPUT OF VARIABLE DISPLACEMENT PUMPS Filed March 14, 1949 a Sheets-Sheet 2 INVENTOR. Fl. 1"

AT'TONEYS y 1952 G. J, E. HOWARD 2,597,799

MEANS FOR CONTROLLING THE OUTPUT OF VARIABLE DISPLACEMENT PUMPS Filed March 14, 1949 I 3 Sheets-Sheet 3 I 3 I2 I v I 11/ I I I I 4 I I I 11 V Y FIG.- 3

PIC-3.4

FIGQS INYENTOR ATTORNEYS Patented May 20, 1952 MEANS FOR CONTROLLING THE OUTPUT OF VARIABLE DISPLACEMENT PUMPS Geofirey John Eliot Howard, Eccles, England, as-

signor to Harold Moore & Partners (Engineers) Limited, Whyteleafe, England, a company of Great Britain Application March 14, 1949, Serial No. 81,272 Y 2 Claims.

This invention relates to reciprocating piston or plunger pumps of the kind wherein two pistons are driven through differential or other gearing arranged so that the piston phase relationship can be varied for the purpose of varying the capacity of the pump and is an improvement in the pump of the said kind described in the specification of U. S. Patent No. 2,166,873 (H. Moore and H. E. Charlton).

In the aforesaid specification the variation in output is obtained by rotating the central bevel wheel of a differential gear about the axis of the other two bevel wheels of the gear.

According to the present invention the rotation of the aforesaid central bevel wheel or of the spindle carrying the wheel of the epicyclic gear is controlled by a controlling instrument in such a manner that the output of the pump is determined by the impulse received from the instrument.

The invention is illustrated in the accompanying drawings, in which Fig. 1 is a diagram illustrating the invention.

Fig. 2 is a section through the pump and the controlling means.

Figs. 3, 4 and 5 are detail sectional views showing diagrammatically positions of the pistons and valves of the controlling mechanism.

The pump shown in Fig. 2 is of a known type in which twoplungers A and B are reciprocated in a pump chamber C having a liquid inlet and outlet 0 The pump plungers are driven to and fro by eccentrics A and A The eccentric A is fixed on a sleeve (1. which sleeve is driven by the gearing D and the eccentric A is mounted on a sleeve a which receives its motion from the bevel wheel e secured on the sleeve a through the bevel wheel I and the bevel wheel e secured on the sleeve 0, The sleeves a and at are loosely mounted on a shaft 3 mounted in bearings in the gear casing and the bevel wheel I is rotatably mounted on a short shaft 2 secured to and projecting at right angles to the shaft 3. Relative displacement of the eccentrics A and A is ob tained by an angular movement of the shaft 3 which causes a rotation of the bevel wheel e in relation to the bevel wheel e and a consequent displacement of the eccentrics. .g

It is to be understood that the mechanism so far described is known and does not form part per se of the present invention.

In the mechanism alread known, the shaft 3 has been rotated to move the bevel wheel I about the axis of the shaft 3 manually, but in accordance with the present invention, the shaft 3 is rotated from means controlled by impulses from a measuring instrument. I

A crank arm 5 is keyed at one end to the en of the shaft 3 and its other end is connected by means of a pin to a link 6 which is itself connected to a piston rod I fitted with a piston 9 and 9 at each extremity, each piston working in a separate cylinder In and I I respectively. Oil under pressure is supplied to the cylinders Ill and II from a pump F (see Fig. 2) situated in the main pump gear case. The supply of oil is controlled by means of a sleeve valve I2 working in a casing I3 and having a central bore to receive a pilot valve I4. The sleeve valve I2 is connected by means of a rod I5 to a follower I5 which is pressed by a spring I8 against a crank 5a which rotates with the crank arm 5.

Movement of the piston rod 1 will cause the crank arm 5 to rotate the shaft 3 about its axis thereby causing the central bevel wheel I to rotate about the axis of the shaft 3. The rotation of the shaft 3 will also cause the crank 5a to move the sleeve valve I2 through the follower I6 and rod I5.

The pilot valve I4 is connected by a rod I9 either directly or through the intermediary of a bell crank lever, one arm of which may beadjustable, to the actuating member of the controlling unit of a controlling instrument 29, and the whole mechanism is so arranged that the total movement of the pilot valve I4 imparted by the controlling instrument is the same as that of the sleeve valve I2 imparted by the follower I6 corresponding to a change in output of the pump from zero to maximum.

The controlling instrument 23 comprises two plates 3I and 32 respectively, connected together by rods 33 which can slide through apertures in a fixed partition 34. The rod I9 is fixed to the plate 3I between which and the partition 34 an expandable bellows 35 is arranged. A spring 36 is arranged between the partition 34 and the other plate 32. A passage 31 through the partition 34 connects with the interior of the bellows, and this passage may be connected to a controlling instrument, impulses of which vary the pressure within the bellows 35 and so move the pilot valve I4 in one direction or the other.

The valve casing I3 has a central inlet Port 25 connected to the oil pump and two exhaust ports 26 and 21 one at each end thereof. It also has two ports 28 and 29 connected respectively to the cylinders I0 and II The sleeve valve contains two ports 2| and 22 which can be put into communication with the cylinders I0 and II in which the pistons 8 and 9 on the ends of the piston rod 1 work by means of the ports 28 and 29 in the valve casing I3 and these ports 2I and 22 control the supply of oil to the cylinders I0 and II.

The'sleeve valve has a third port 30 connecting with the inlet port 25 in the casing I3, the port 30 being sufficiently long that the port 25 is not covered whatever the position of the sleeve valve I2 may be.

shown in the drawing the two lands cover the two ports 28 and 29 therein.- Oil under pressure is fed to the space betweenfthe two' lainds H and 24 of the pilot valve M throughthe ports" 25 and 30 in the valve casingelli andthe sleeve" valve l2 respectively and the=ports -'2'6'"and 21 in the ends of the valve casinga-reconnectedby' pipes to the sump from which the oil pressure pump F obtains its supply.

It will be apparent that when the pilot valve [4 is in the position with the lands coveringthe two ports 2| and 22 in the sleeve valve 12, movement of oil' to or from the two cylinders Ill and It is prevented and 'the pistons 8 and! therein are locked in position whereby the shaft 3 is-prevented ffromiro'tating' and: the central beverwheel I is fii r'ed in osition;

Suppose now that an impulse from" the mea's urine instrum'ent -Z-Q moves the rod' [9 connected to the pilot 'valve' lt-and' therebyithe -'latter a certain distan'ce' to the left corresponding to a definite change in output required from the pump the ports 22 and 2| in the sleeve *val've12 will be uncovered. and-the port 29 in the valve casing'will' be put-intocommunication with the sumpithrou'gh the portn and the open end of the valveii' and the oil pressure in the cylinder It will be"released;- The port 'Zlin the sleeve valve 'lz will a lso be' put into communication \vithj'the pressureoil supplythrough the centre of the pilot valve I4 and the ports 30 and 25 and thus oilpre'ssure 'willbe- 'applied to the-cylinder lfl and'causethe pistons 8- and-9 td-move to the right. This movement will rotatetheshaft 3 in: air anticlockwise direction through the piston rod Li link- 6 and; cranli' -5 thus causi-ng'zthe output of the pump Vito" alter owing .-tothe rotation of thecentralbevel wheel I about the axis of-the shaft 3.-

At' the-same' timetheend ll of the crank be will also rotate in an anticlockwise direction about the axis of the shaft -3 and thus allow the spring- 1 fi-to-move the follower Hi to the left and this-in turn: moves thesleeve valve- I2 to the left through the follower rodl6.

This movement will continue until the sleeve valve H. has moved into such a position that the ports- 2i and 22 are againcovered by the lands 23-and 2 t of the'pilot valve Hi when the-system becomes hydraulically lockedand movement ceases:

From the above description it will be understood that' no matter in what position the: pilot valve I4 may be, the shaft 3 will-always rotate until the sleeve valve l2 has its ports Hand 22 covered by the lands 2 3 and '24 of the pilot valve.

Asthe distance moved bythe follower Hi from the zero position is-arrangedto be proportional to the output of the pump-lit-will beseen that the sleeve valve l2 and thus the follower always comes to-rest at a position indicated by the instrument 2a through the pilot valve l l'.

Thus the ouput of t-he pump will always be proportional to the amount 'ofmovement imparted to the pilot valve 14' by the bellows 35 of the-= controlling unit.

As both ends of the pilot valve I4 and the sleeve valve l2 are-in communication with-the sump of the pum-plF it follows that both' these valves are balanced and that the amount of effort required tomove them is small and that the sensitivity-l ofl-theapparatus is thereby increased.

mam-1:- 1. In a reciprocating piston pump of the kind in which two pistons are moved to and fro by eccentrics one of which is positively driven and the othe'-rdriven therefrom through a differeritiafgear comprising a pair of bevel wheels and;a co0perating-central bevel wheel, and arranged 'sothat 'the piston phase relationship is 'vari'abl'e'tovary the capacity of the pump by rotationofthecentral bevel wheel about the axis of thepair of bevel wheels of the gear, the combination of a shaft carrying the said central beVelwheel, a second shaft to which the first shaft is aflixed and which is co-axial with the axes-or the pair of bevel" wheels and arranged at right; angles to *the first shaft; of two cylinders and' a "piston: in each 1 cylinder, a co'mm 'on piston rod for the two pistons; means counecifingre'the pistori rod to said second" shaft for converting-a longitudinal movement of said rod into a rotary movement of the second shaft, a valve control l ing. the supply of fluid to the aforesaid cylinders to operate the pistons, anda'controllin'g instru' ment operative to produce" impulses to' actuate the'va'lvawhereby the rotatio'n of the central bevel wheel is actuated by and consequently-the outlet of the pump is controlleclby'the' aforesaid impulses;

2; In a 'reciprocating 'piston pump of the kind in which two pistons are moved to and fro-by eccentrics one of which'is positively driven and the other driven therefrom" through a differential gear co'mprisin'g' ;a-pair ofbev wheels and a cooperating central bevel wheels-anaerrang e'd so that the pistonphase relationship is variable to vary the capacity" ofth pinnpffby rotation of the central :bev'el" wheel about the axis'of the: pair of bevel 'wh'el's of the gearthe combination of a shaft carrying the said c'entfal bevel :wheel, a second shaft towhichthe-first shaft is aifixed' and which is' co-aiiial with the axes of the said-pair' of bevel"wheels' at right angles to the first shaft,-two' cylinders and a piston in each cylinder; a common" piston rod forth two' pistons, a crankarmiconnecting-said second" shaft with the "pistons whereby a longi"- tudinal movement of said rod" is converted into a rotary movement-"of the' second shaft,"a sleeve valverhavirig a central bore and ports for" controlling. the supply of: fluid-to the" aforesaid cylinders to operate'the pistons therein; a spring controlled rod carried by f the sleeve valve: and abutting against the crank *arm, a 'pilot" valve slidabl'y mounted -in-the central bore'ofi'the sleeve valve; and a'controlling' instrument 'corinected to the pilot valve and operative to" pro duce impulses to actuate the: pilot valve "and through the sleeve valve control the supply 1: 'of fluid to the cylindersirr whiohthe pistons operating the firstashaft are located:

GEOFFREY JOHN ELIOT REFERENCES" CITED The-"following" *refe'rences are of record the file of this patent:

UNITED STATES" PATENTS Number Name Date ass-per Flinn. Apn-28, .1903 1,502,195 Hicks, Jrl-' July 221- 1924 1,965,283 Hillier July 3,: 1 934: 2,166,823 Moore, et al. July"18,'l'934 2,166,873 Moore, et al'. Dec.2'0,1'937 

